Recent efforts have been directed in developing chips for molecular detection. Of particular interest are DNA chips for sequencing and diagnostic applications. A DNA chip includes an array of chemically-sensitive binding sites having single-stranded DNA probes or like synthetic probes for recognizing respective DNA sequences. The array of binding sites is typically arranged in a rectangular grid.
A sample of single-stranded DNA is applied to the binding sites of the DNA chip. The DNA sample attaches to DNA probes at one or more of the binding sites. The sites at which binding occurs are detected, and one or more molecular structures within the sample are subsequently deduced.
In sequencing applications, a sequence of nucleotide bases within the DNA sample can be determined by detecting which probes have the DNA sample bound thereto. In diagnostic applications, a genomic sample from an individual is screened with respect to a predetermined set of probes to determine if the individual has a disease or a genetic disposition to a disease.
Many diagnostic devices and methods perform an invasive test requiring a blood sample to be extracted from an end user. For example, most commercially-available portable blood glucose meters require an end user to prick his/her finger with a lancet to perform a blood glucose level test. After pricking his/her finger, the end user deposits a drop of blood onto a test strip. The sample of blood on the test strip is tested by the glucose meter to determine a glucose level. Since a typical end user with diabetes performs the above-described invasive test four times a day, the need exists for a noninvasive apparatus to perform blood glucose level tests.
HIV testing is another diagnostic procedure which uses an invasively-extracted sample of blood. This procedure and other diagnostic procedures also would benefit from a noninvasive apparatus designed therefor.